In general, different integrated circuits can have different power supply requirements. Further, an integrated circuit may utilize multiple regulated power supplies at various power levels, such as 5V, 3.3V, 2.8V, 2.5V, 2.0V, 1.8V, 1.5V, 1.2V, 0.9V, other voltage levels, or any combination thereof. Generally, electronic devices include multiple voltage regulator circuits to generate the multiple stable output voltages from a varying input supply voltage. A voltage regulator is a circuit that is adapted to automatically maintain a constant output voltage at a desired voltage level.
Multiple power supplies may be provided using multiple fixed power regulator circuits to produce multiple output voltages. In a particular instance, a programmable power regulator may be used, where the output voltage signal provided by the programmable power regulator can be adjusted by adjusting a gain of a buffer circuit or attenuation circuit coupled to the programmable power regulator.
In some instances, a power regulator circuit can include several voltage regulators, including one or two voltage regulators that can be adjusted with respect to a single parameter and within a limited range. For example, a particular voltage regulator circuit includes two programmable voltage regulators that have fixed output currents but that can be adjusted to provide an output voltage within a range from 0.6 volts to 3.3 volts, depending on the configuration of the feedback network. However, such power regulator circuits typically provide few, if any, configurable options. Accordingly, the power regulator circuit is typically designed as a particular type of voltage regulator and is typically adjusted for each particular implementation.